Naturespeak A naturalist's view of the world

May 26, 2008

Pre-ripened Chicks

Filed under: Uncategorized — wykes @ 4:12 pm

  Killdeer chicks are among the cutest (can you say “Ka-Yoot!”) of all baby birds but they can’t rely solely on their leggy good looks to get them through early life.  They need to enter onto the world stage a step ahead of most other avian young because the world is already a step ahead of them. Their parents started them off in an exposed ground nest- a mere scrape in the soil surrounded by short grass or gravel.

  As eggs they were protected by a cryptically camouflaged egg pattern which made them virtually invisible. This vulnerable stage lasts for 24-28 days during which time the vigilant adult birds incubate and keep a watchful eye out for predators. Upon hatching, the chicks have another danger ridden month to go until they can fly.

  From the moment they exit the egg, the chicks are expected to get up and out of the nest scrape as soon as possible. They are precocial – a term which means they are ready from the get-go. In Latin, this word means something like “ripened beforehand” or “early maturing” (using the same root word used to describe a human youngster who is “precocious” and advanced beyond their years). Chickens, ducks, rails, and pheasants also have precocial young. These birdlets spend a long time ripening inside a relatively large egg and thus emerge with large heads, open eyes, strong legs and a full coat of downy fluff.  They can feed themselves soon after hatching.

  Precocial chicks are tough customers. One killdeer baby survived a seven story drop after it launched off the top of a gravel top roof where the nest was located. Wood Duck young routinely drop great distances from their tree hole nests and bounce harmlessly off the hard ground!

  Altricial birds, such as robins, are born helpless, blind, and naked.  Altricial means “to nourish” and such birds need to have food brought to them by a wet nurse, so to speak.  In theory, an altricial bird is about two weeks behind a precocial bird upon hatching. But, it is important to note that such birds also are brought up in secure locations and are in less immediate danger than the precocial sort.

  Even though killdeer chicks can locate their insect food on their own, they still need some degree of parental protection during the long pre-flight stage. I stumbled upon a group of newly hatched killdeer the other day and was delighted to see the adult bird gallantly going through her broken wing act in order to lure me away. The chicks scattered about (see here) while mom acted as a decoy. Three out of the four young scampered across the road and easily put distance between me and them. These chicks are endowed with disproportionately long legs and they can put them to use with great effect.

  The fourth chick, however, found itself somewhat cornered. It hesitated and couldn’t manage the end run before I closed the distance. At this point, it immediately employed another trick from the instinctual playbook – it stepped into a patch of slightly longer grass, crouched down, and froze into position.

  Like the eggs they came from, the chicks are cryptically colored. When fully pressed to the ground (like this) they are very hard to see. I was able to get this picture only because I saw exactly where this killdeer fawn stopped and dropped. I parted the grass in order to get a better shot and the bird remained motionless (see here).

  That ability to freeze and remain frozen is a crucial part of the plan. It resisted the urge to bolt even when I moved it slightly while moving one of the grass stems. The tiny bird performed the routine like a practiced pro even though it was only a few hours old.

  As an altricial human being, who was unable to do anything but cry when only a few hours old, I was impressed.

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